The present invention relates generally to detection of the onset of rapid (acute) symptomatic drop in a subject's blood pressure. More particularly, the invention relates to an alarm apparatus, a medical system, a method, a computer program, and a computer readable medium.
There exist many situations wherein it is important to detect potential hypotension, and if possible avoid the actual occurrence thereof, for example when performing artificial blood purification. The human body consists of approximately 60% water—a level which is important to maintain for survival. While it is unproblematic to provide the body with new water, disposal of surplus water is a major problem in renal patients. The task of the normal kidney is to remove superfluous fluid from the blood, such as water, urea and other waste products. The resulting urine is transferred to the bladder and finally leaves the body during urination. The kidney's second task is to regulate for example the balance of acid and base. With malfunctioning kidneys, disorders may develop in most major body organs, a syndrome called uremia. If uremia remains untreated, it will lead to death. Uremia is treated either by kidney transplantation, or some kind of blood treatment, extracorporeal or intracorporeal.
During an artificial blood purification process, such as extracorporeal blood treatment, it is common that the patient suffers from symptomatic hypotension, characterized by a blood pressure drop with symptoms in the form of cramps, nausea, vomiting and sometimes fainting. Such an event is not only strenuous for the patient, but also requires considerable attention from the staff overseeing the treatment. Consequently, during such blood treatment, it is highly desirable to detect the onset of symptomatic hypotension and preventing it from coming about.
However, there are other examples of situations in which it is vital to predict, and if possible prevent, rapid symptomatic hypotension. For instance fighter plane pilots are often subjected to forces that risk result in that the pilot faints. However, also operators of other types of vehicles, crafts and machines may need similar surveillance in order to reduce hazards to the operators, other people and various material goods.
The published US patent application 2004/0254473 describes a laser blood-flow meter and a system for monitoring bio-data of a person. The laser blood-flow meter measures a respective blood flow in different quarters of a biological structure by irradiating laser beams to the structure and detecting resulting scattered beams. Based on the detected light, it is then judged whether the person to which the biological structure belongs is in a serious condition. For example, this judgement may be based on a reduction in blood flow relative to previously recorded standards, reduction in an amplitude of a blood-flow waveform relative to the standards, and a heartbeat frequency increase.
However, there is yet no solution, which on one hand, provides a quick and reliable hypotension warning, and on the other hand, is cost-efficient and straightforward to implement.